one of the organizers for the Hurricane / Southside Festival hinted that Muse are playing the two Festivals by writing in the official Southside forums that he "just talked to Matthew about when they will meet to trink port wine on Friday".
This would make the following schedule possible:
Friday, 27th June: Southside Festival
Saturday, 28th June: Bremen gig
Sunday, 29th June: Hurricane Festival
Because Scheeßel is very close to Bremen (and a lot of people will be there), a possible gig in Bremen would be a club show, possibly at the Aladin, where Muse played... 2001 (?). Capacity at this venue is 2.000 or 3.000 I think...